Contents

Btrfs

Initial support for Btrfs was introduced in Syslinux 4.06.
Several improvements and fixes were added in later versions.
Syslinux 6.03 (or later) is recommended.

As of Syslinux 6.03,
Btrfs' multi-device volumes are not supported.

As of Syslinux 6.03,
the compression and/or encryption features of Btrfs volumes
are not supported.
In other words,
Syslinux cannot find (configuration / kernel / initrd)
files if the boot filesystem is compressed and/or encrypted.

ext

As of Syslinux 6.03, "pure 64-bits", compression and/or encryption
are not supported.

Quoting part of the release notes of
version 1.43 of e2fsprogs (May 17, 2016):

Mke2fs will now create file systems with the metadata_csum and 64bit features enabled by default.

Users should rather (manually) disable the 64bit feature
in the mke2fs command when creating / formatting
a boot volume with ext4;
otherwise, the bootloader (as of version 6.03) will fail.

Notes:

For a 4KiB block size, an ext2/3/4 volume size of less than 16TiB when created without the "64bit feature" is supported by Syslinux as of version 6.03.

To manually disable the "64bit" feature when creating ext4 volumes, use -O ^64bit in the mke2fs (or equivalent) command. That is, an hyphen, immediately followed by an upper-case letter "O", a space character, the caret "^" symbol, followed by "64bit" (no hyphen).

In some cases, a backslash character before the caret might be needed: -O \^64bit

In resize2fs, the -s parameter (that is, an hyphen followed by a lower-case letter "s") disables the "64bit" feature of an already-created filesystem volume, if its size allows it.

As of Syslinux 6.03,
EXTLINUX does not support symlinks on NTFS volumes.

UFS

Syslinux 6.03 adds support for UFS/FFS in little-endian
architectures (x86 and x86-64).
UFS1 and UFS2 are both supported.

The author of UFS/FFS, Kirk McKusick, said about the name:

The code is broken into two parts,
the part that handles naming (UFS where the U stands for Unix),
and the part that handles disk layout (FFS where the F stands for Fast).
When the two parts are put together they are called UFS/FFS or more commonly just UFS.

UFS notes

The following steps were initially only made under a GNU/Linux environment. Therefore, functionality might vary on other systems.

Dependency: ufsutils (UFS filesystems utilities) or equivalent.

To add Write support on UFS to Linux, a kernel with the option CONFIG_UFS_FS_WRITE enabled is needed, or at least configured as a module. To the latter case, load the module "ufs.ko" with modprobe (probably located at "/lib/modules/").